Timing off 180 degrees???
#1
Timing off 180 degrees???
Quick question: when you align the flats on the cams, is it possible for the timing to be off 180 degrees, ie that you should make another revolution on the main crank?
Back story: I bought an '99 XJ8 super cheap for the drivetrain and other parts that crossover as a parts car for my XK8. Passenger tensioner was blown. I wanted to determine whether the valves were toast before I pulled the motor, so I put in a tensioner from the XK8 replacement (only meant to be temporary), bought a new timing chain, aligned the flats on the cams and put the chain on. Cranked on the engine and it seems like it is majorly out of time.
Also, would being one tooth off cause it to be majorly out of time? I am pretty sure it was on but may take another look.
B
Back story: I bought an '99 XJ8 super cheap for the drivetrain and other parts that crossover as a parts car for my XK8. Passenger tensioner was blown. I wanted to determine whether the valves were toast before I pulled the motor, so I put in a tensioner from the XK8 replacement (only meant to be temporary), bought a new timing chain, aligned the flats on the cams and put the chain on. Cranked on the engine and it seems like it is majorly out of time.
Also, would being one tooth off cause it to be majorly out of time? I am pretty sure it was on but may take another look.
B
#2
#3
Join Date: Oct 2007
Location: PHX some of the time
Posts: 117,691
Received 6,339 Likes
on
5,524 Posts
#4
Not sure what you mean Spark. And no Norri, i did not use any tools.
When I did the tensioner job on my XK8, I did the zip tie method and it worked great. The cam flat spots were parallel.
That is what I am asking about this job, can one blindly "time" the secondary cam to the main cam just by making sure that the flat spots are parallel???
When the tensioner blew, the chain jumped the sprocket. I bought a new chain and am trying to get the secondary cam back in time.
B
When I did the tensioner job on my XK8, I did the zip tie method and it worked great. The cam flat spots were parallel.
That is what I am asking about this job, can one blindly "time" the secondary cam to the main cam just by making sure that the flat spots are parallel???
When the tensioner blew, the chain jumped the sprocket. I bought a new chain and am trying to get the secondary cam back in time.
B
#5
#7
Join Date: Oct 2009
Location: Perth Ontario Canada
Posts: 11,058
Received 2,266 Likes
on
1,845 Posts
Trending Topics
#8
DSnyder, I think my eyeballs work pretty good in seeing they are aligned, I believe a cog off would be noticeable. However, I am open to the idea. Have you done so or can I search for it?
Steve, That is what i am asking. The hillbillies i bought it from said the car would start when i bought it (with the secondary chain off the pulley). I didnt want to chance it and changed the timing chain and put in a temporary tensioner. I cranked the car yesterday and while there was no loud noise, it wouldn't start acting like it was out of time. But it cranked fairly smooth.
B
Steve, That is what i am asking. The hillbillies i bought it from said the car would start when i bought it (with the secondary chain off the pulley). I didnt want to chance it and changed the timing chain and put in a temporary tensioner. I cranked the car yesterday and while there was no loud noise, it wouldn't start acting like it was out of time. But it cranked fairly smooth.
B
#9
Join Date: Oct 2007
Location: PHX some of the time
Posts: 117,691
Received 6,339 Likes
on
5,524 Posts
Beep,
There's a locating pin that goes into the flex plate to hold the crank in the correct position when aligning the cam flats.
IIRC it goes into the same hole that the crank position sensor is in.
As you have had the chain off you need to go back to square one and set up from scratch.
There's plenty of threads with the details but this one shows some do it yourself tools.
There's a locating pin that goes into the flex plate to hold the crank in the correct position when aligning the cam flats.
IIRC it goes into the same hole that the crank position sensor is in.
As you have had the chain off you need to go back to square one and set up from scratch.
There's plenty of threads with the details but this one shows some do it yourself tools.
#10
#11
OK, so as I understand it, I lock the crank with something similar to the attached .pdf. Once I have got the crank in the correct place, I should make sure that both pairs of cams are in perfect alignment using some flat object or tool. Correct?
My confusion still is: being one secondary cam (what is the cam the secondary timing chain attaches to?) is the only thing to go out of alignment due to the timing chain jumping the pulley, shouldn't I ONLY have to align the secondary cam with the main cam on the same side?
B
My confusion still is: being one secondary cam (what is the cam the secondary timing chain attaches to?) is the only thing to go out of alignment due to the timing chain jumping the pulley, shouldn't I ONLY have to align the secondary cam with the main cam on the same side?
B
#12
Join Date: Oct 2009
Location: Perth Ontario Canada
Posts: 11,058
Received 2,266 Likes
on
1,845 Posts
#13
The exhaust cam is on the secondary chain. It's the lower one on the head. If the flats line up and the primary chain has not been disconnected I don't see how the timing could be off.
From what I have read here, the secondary chain was broken. This almost HAS to result in bent valves at the least.
From what I have read here, the secondary chain was broken. This almost HAS to result in bent valves at the least.
#15
The exhaust cam is on the secondary chain. It's the lower one on the head. If the flats line up and the primary chain has not been disconnected I don't see how the timing could be off.
From what I have read here, the secondary chain was broken. This almost HAS to result in bent valves at the least.
From what I have read here, the secondary chain was broken. This almost HAS to result in bent valves at the least.
That is what I am trying to determine, if the valves are bent. I got the whole car for $500, mainly for the tranny. I want to know if the motor is good or toast BEFORE I yank it out of the car.
Thanks everyone for helping me get to the bottom of this.
B
#16
You can pull the exhaust cam out of the side that broke the chain and run compression tests- the intake cam is ostensibly still in time so with the exhaust cam out- no problem.
UNLESS the valves are severely bent- make sure to turn the crank by hand (only in the correct direction!) before running the compression tests.
UNLESS the valves are severely bent- make sure to turn the crank by hand (only in the correct direction!) before running the compression tests.
Thread
Thread Starter
Forum
Replies
Last Post
Wolfy
XJ ( X351 )
58
05-28-2024 08:06 AM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)